1. Field of the Invention
The present invention relates to an audio signal processing apparatus, audio signal processing method and audio processing program, and is preferably applied to the control of the spread of sound image by arbitrarily changing the position of sound image localization that a listener feels makes a predetermined angle inside a room or other acoustic spaces, for example.
2. Description of the Related Art
Usually, various audio sources are included in content recorded on Compact Disc (CD), Digital Versatile Disc (DVD) and the like, and audio signals such as TV broadcasting content. For instance, the music content may include voice and sound of instruments and the like. The TV broadcasting content may include voice of performers, effective sound, laughing voice, handclap sound and the like.
Those audio sources are usually recoded by separate microphones at the site. They are finally converted into audio signals with a predetermined number of channels, such as two-channel audio signals.
There are methods of Virtual Surround to make the listener feel bigger acoustic space than usual as for two-channel audio signals: a method in which a surround speaker outputs a waved signal of a difference between a right-channel audio signal and a left-channel audio signal; and a sound image and acoustic space control device with the capability of crosstalk canceller (see Jpn. Pat. Laid-open Publication No. H8-146974, for example) that outputs sound to cancel improper sound to allow the listener to locate a virtual audio source (the listener may not be able to locate the virtual audio source if the sound for a left ear reaches his/her right ear).